Publications by authors named "Silvia Bisti"

38 Publications

Retinal Neurodegeneration: Correlation between Nutraceutical Treatment and Animal Model.

Nutrients 2021 Feb 27;13(3). Epub 2021 Feb 27.

Interuniversity Consortium -Biostructures and Biosystems National Institute (INBB), Via Medaglie d'Oro 305, 00136 Roma, Italy.

Retinal diseases can be induced by a variety of factors, including gene mutations, environmental stresses and dysmetabolic processes. The result is a progressive deterioration of visual function, which sometimes leads to blindness. Many treatments are under investigation, though results are still mostly unsatisfactory and restricted to specific pathologies, particularly in the case of gene therapy. The majority of treatments have been tested in animal models, but very few have progressed to human clinical trials. A relevant approach is to study the relation between the type of treatments and the degenerative characteristics of the animal model to better understand the effectiveness of each therapy. Here we compare the results obtained from different animal models treated with natural compounds (saffron and naringenin) to anticipate the potentiality of a single treatment in different pathologies.
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http://dx.doi.org/10.3390/nu13030770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997156PMC
February 2021

Saffron: Chemical Composition and Neuroprotective Activity.

Molecules 2020 Nov 29;25(23). Epub 2020 Nov 29.

National Institute of Biostructure and Biosystem (INBB), V. le Medaglie D'Oro 305, 00136 Roma, Italy.

L. belongs to the Iridaceae family and it is commonly known as saffron. The different cultures together with the geoclimatic characteristics of the territory determine a different chemical composition that characterizes the final product. This is why a complete knowledge of this product is fundamental, from which more than 150 chemical compounds have been extracted from, but only about one third of them have been identified. The chemical composition of saffron has been studied in relation to its efficacy in coping with neurodegenerative retinal diseases. Accordingly, experimental results provide evidence of a strict correlation between chemical composition and neuroprotective capacity. We found that saffron's ability to cope with retinal neurodegeneration is related to: (1) the presence of specific crocins and (2) the contribution of other saffron components. We summarize previous evidence and provide original data showing that results obtained both "in vivo" and "in vitro" lead to the same conclusion.
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http://dx.doi.org/10.3390/molecules25235618DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7731018PMC
November 2020

Biocompatibility of a Conjugated Polymer Retinal Prosthesis in the Domestic Pig.

Front Bioeng Biotechnol 2020 15;8:579141. Epub 2020 Oct 15.

Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.

The progressive degeneration of retinal photoreceptors is one of the most significant causes of blindness in humans. Conjugated polymers represent an attractive solution to the field of retinal prostheses, and a multi-layer fully organic prosthesis implanted subretinally in dystrophic Royal College of Surgeons (RCS) rats was able to rescue visual functions. As a step toward human translation, we report here the fabrication and testing of a similar device engineered to adapt to the human-like size of the eye of the domestic pig, an excellent animal paradigm to test therapeutic strategies for photoreceptors degeneration. The active conjugated polymers were layered onto two distinct passive substrates, namely electro-spun silk fibroin (ESF) and polyethylene terephthalate (PET). Naive pigs were implanted subretinally with the active device in one eye, while the contralateral eye was sham implanted with substrate only. Retinal morphology and functionality were assessed before and after surgery by means of optical coherence tomography and full-field electroretinogram (ff-ERG) analysis. After the sacrifice, the retina morphology and inflammatory markers were analyzed by immunohistochemistry of the excised retinas. Surprisingly, ESF-based prostheses caused a proliferative vitreoretinopathy with disappearance of the ff-ERG b-wave in the implanted eyes. In contrast, PET-based active devices did not evoke significant inflammatory responses. As expected, the subretinal implantation of both PET only and the PET-based prosthesis locally decreased the thickness of the outer nuclear layer due to local photoreceptor loss. However, while the implantation of the PET only substrate decreased the ff-ERG b-wave amplitude with respect to the pre-implant ERG, the eyes implanted with the active device fully preserved the ERG responses, indicating an active compensation of the surgery-induced photoreceptor loss. Our findings highlight the possibility of developing a new generation of conjugated polymer/PET-based prosthetic devices that are highly biocompatible and potentially suitable for subretinal implantation in patients suffering from degenerative blindness.
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http://dx.doi.org/10.3389/fbioe.2020.579141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7605258PMC
October 2020

Saffron Crudes and Compounds Restrict MACC1-Dependent Cell Proliferation and Migration of Colorectal Cancer Cells.

Cells 2020 08 3;9(8). Epub 2020 Aug 3.

Experimental and Clinical Research Center, Charité-Universitätsmedizin Berlin, and Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.

The high mortality rate of colorectal cancer (CRC) patients is directly associated with metastatic dissemination. However, therapeutic options specifically for metastasis are still limited. We previously identified Metastasis-Associated in Colon Cancer 1 (MACC1) as a major causal metastasis-inducing gene. Numerous studies confirmed its value as a biomarker for metastasis risk. We investigated the inhibitory impact of saffron on MACC1-induced cancer cell growth and motility. Saffron crudes restricted the proliferation and migration of MACC1-expressing CRC cells in a concentration- and MACC1-dependent manner. Saffron delays cell cycle progression at G2/M-phase and does not induce apoptosis. Rescue experiments showed that these effects are reversible. Analysis of active saffron compounds elucidated that crocin was the main compound that reproduced total saffron crudes effects. We showed the interaction of MACC1 with the cancer stem cell (CSC) marker DCLK1, which contributes to metastasis formation in different tumor entities. Saffron extracts reduced DCLK1 with crocin being responsible for this reduction. Saffron's anti-proliferative and anti-migratory effects in MACC1-expressing cells are mediated by crocin through DCLK1 down-regulation. This research is the first identification of saffron-based compounds restricting cancer cell proliferation and motility progression via the novel target MACC1.
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http://dx.doi.org/10.3390/cells9081829DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463853PMC
August 2020

Effects of Cord Blood Serum (CBS) on viability of retinal Müller glial cells under in vitro injury.

PLoS One 2020 4;15(6):e0234145. Epub 2020 Jun 4.

Ophthalmology Unit, DIMES, Alma Mater Studiorum University of Bologna, S.Orsola-Malpighi Teaching Hospital, Bologna, Italy.

Oxidative stress and inflammation determine retinal ganglion cell degeneration, leading to retinal impairment and vision loss. Müller glial cells regulate retinal repair under injury, through gliosis. Meanwhile, reactive gliosis can turn in pathological effects, contributing to neurodegeneration. In the present study, we tested whether Cord Blood Serum (CBS), rich of growth factors, might improve the viability of Müller cells under in vitro damage. BDNF, NGF, TGF-α, GDNF and EGF levels were measured in CBS samples by Human Magnetic Luminex Assay. CBS effects were evaluated on rat (rMC-1) and human (MIO-M1) Müller cells, under H2O2 and IL-1β damage. Cells grown with FBS or CBS both at 5% were exposed to stress and analyzed in terms of cell viability, GFAP, IL-6 and TNF-α expression. CBS was also administrated after treatment with K252a, inhibitor of the neurotrophin receptor Trk. Cell viability of rMC-1 and MIO-M1 resulted significantly improved when pretreated with CBS and exposed to H2O2 and IL-1β, in comparison to the standard culture with FBS. Accordingly, the gliosis marker GFAP resulted down-regulated following CBS priming. In parallel, we observed a lower expression of the inflammatory mediators in rMC-1 (TNF-α) and MIO-M1 (IL-6, TNF- α), especially in presence of inflammatory damage. Trk inhibition through K252a administration impaired the effects of CBS under stress conditions on MIO-M1 and rMC-1 viability, not significantly different from FBS condition. CBS is enriched with neurotrophins and its administration to rMC-1 and MIO-M1 attenuates the cytotoxic effects of H2O2 and IL-1β. Moreover, the decrease of the main markers of gliosis and inflammation suggests a promising use of CBS for neuroprotection aims. This study is a preliminary basis that prompts future investigations to deeply explore and confirm the CBS potential.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0234145PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7272066PMC
August 2020

Cord Blood Serum (CBS)-Based Eye Drops Modulate Light-Induced Neurodegeneration in Albino Rat Retinas.

Biomolecules 2020 04 28;10(5). Epub 2020 Apr 28.

Ophthalmology Unit, University of Bologna and S. Orsola-Malpighi Teaching Hospital, 40138 Bologna, Italy.

Age-related macular degeneration (AMD) is one of the leading causes of visual loss in western countries, it has no cure, and its incidence will grow in the future, for the overall population aging. Albino rats with retinal degeneration induced by exposure to high-intensity light (light-damage, LD) have been extensively used as a model of AMD to test neuroprotective agents. Among them, trophic factors (NGF and BDNF) have been shown to play a significant role in photoreceptors' survival. Interestingly, cord blood serum (CBS) is an extract full of chemokines and trophic factors; we, therefore, hypothesized that CBS could be an excellent candidate for neuroprotection. Here, we investigate whether CBS-based eye drops might mitigate the effects of light-induced retinal degeneration in albino rats. CBS treatment significantly preserved flash-electroretinogram (f-ERG) response after LD and reduced the "hot-spot" extension. Besides, CBS-treated animals better preserved the morphology of the outer nuclear layer, together with a reduction in microglia migration and activation. Interestingly, the treatment did not modulate reactive gliosis and activation of the self-protective mechanism (FGF2). In conclusion, our results suggest that CBS-based eye drops might be successfully used to mitigate retinal neurodegenerative processes such as AMD.
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http://dx.doi.org/10.3390/biom10050678DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7277721PMC
April 2020

Antioxidant Saffron and Central Retinal Function in ABCA4-Related Stargardt Macular Dystrophy.

Nutrients 2019 Oct 15;11(10). Epub 2019 Oct 15.

Dipartimento di Scienze dell'Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, Fondazione Policlinico Universitario A. Gemelli- IRCCS, 00168 Rome, Italy.

Retinal oxidative damage, associated with an ATP-binding cassette, sub-family A, member 4, also known as ABCA4 gene mutation, has been implicated as a major underlying mechanism for Stargardt disease/fundus flavimaculatus (STG/FF). Recent findings indicate that saffron carotenoid constituents crocins and crocetin may counteract retinal oxidative damage, inflammation and protect retinal cells from apoptosis. This pilot study aimed to evaluate central retinal function following saffron supplementation in STG/FF patients carrying ABCA4 mutations.

Methods: in a randomized, double-blind, placebo-controlled study (clinicaltrials.gov: NCT01278277), 31 patients with ABCA4-related STG/FF and a visual acuity >0.25 were randomly assigned to assume oral saffron (20 mg) or placebo over a six month period and then reverted to P or S for a further six month period. Full ophthalmic examinations, as well as central 18° focal electroretinogram (fERG) recordings, were performed at baseline and after six months of either saffron or placebo. The fERG fundamental harmonic component was isolated by Fourier analysis. Main outcome measures were fERG amplitude (in µV) and phase (in degrees). The secondary outcome measure was visual acuity.

Results: supplement was well tolerated by all patients throughout follow-up. After saffron, fERG amplitude was unchanged; after placebo, amplitude tended to decrease from baseline (mean change: -0.18 log µV, < 0.05). Reverting the treatments, amplitude did not change significantly. fERG phase and visual acuity were unchanged throughout follow-up.

Conclusions: short-term saffron supplementation was well tolerated and had no detrimental effects on the electroretinographic responses of the central retina and visual acuity. The current findings warrant further long-term clinical trials to assess the efficacy of saffron supplementation in slowing down the progression of central retinal dysfunction in ABCA4-related STG/FF.
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http://dx.doi.org/10.3390/nu11102461DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835540PMC
October 2019

Saffron: A Multitask Neuroprotective Agent for Retinal Degenerative Diseases.

Antioxidants (Basel) 2019 Jul 17;8(7). Epub 2019 Jul 17.

Facolta' di Medicina e Chirurgia, Fondazione Policlinico A. Gemelli, Universita' Cattolica del S. Cuore, 00136 Roma, Italy.

Both age related macular degeneration (AMD) and light induced retinal damage share the common major role played by oxidative stress in the induction/progression of degenerative events. Light damaged (LD) rats have been widely used as a convenient model to gain insight into the mechanisms of degenerative disease, to enucleate relevant steps and to test neuroprotectants. Among them, saffron has been shown to ameliorate degenerative processes and to regulate many genes and protective pathways. Saffron has been also tested in AMD patients. We extended our analysis to a possible additional effect regulated by saffron and compared in AMD patients a pure antioxidant treatment (Lutein/zeaxanthin) with saffron treatment. Animal model. Sprague-Dawley (SD) adult rats, raised at 5 lux, were exposed to 1000 lux for 24 h and then either immediately sacrificed or placed back at 5 lux for 7 days recovery period. A group of animals was treated with saffron. We performed in the animal model: (1) SDS-PAGE analysis; (2) Western Blotting (3) Enzyme activity assay (4) Immunolabelling; in AMD patients: a longitudinal open-label study 29 (±5) months in two groups of patients: lutein/zeaxanthin (19) and saffron (23) treated. Visual function was tested every 8 months by ERG recordings in addition to clinical examination. Enzymatic activity of MMP-3 is reduced in LD saffron treated retinas and is comparable to control as it is MMP-3 expression. LD treated retinas do not present "rosettes" and microglia activation and migration is highly reduced. Visual function remains stable in saffron treated AMD patients while deteriorates in the lutein/zeaxanthin group. Our results provide evidence of an additional way of action of saffron treatment confirming the complex nature of neuroprotective activities of its chemical components. Accordingly, long term follow-up in AMD patients reveals an added value of saffron supplementation treatment compared to classical antioxidant protocol.
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http://dx.doi.org/10.3390/antiox8070224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6681062PMC
July 2019

Acquired Resilience: An Evolved System of Tissue Protection in Mammals.

Dose Response 2018 Oct-Dec;16(4):1559325818803428. Epub 2018 Dec 27.

College of Health Sciences, University of Wisconsin, Milwaukee, WI, USA.

This review brings together observations on the stress-induced regulation of resilience mechanisms in body tissues. It is argued that the stresses that induce tissue resilience in mammals arise from everyday sources: sunlight, food, lack of food, hypoxia and physical stresses. At low levels, these stresses induce an organised protective response in probably all tissues; and, at some higher level, cause tissue destruction. This pattern of response to stress is well known to toxicologists, who have termed it hormesis. The phenotypes of resilience are diverse and reports of stress-induced resilience are to be found in journals of neuroscience, sports medicine, cancer, healthy ageing, dementia, parkinsonism, ophthalmology and more. This diversity makes the proposing of a general concept of induced resilience a significant task, which this review attempts. We suggest that a system of stress-induced tissue resilience has evolved to enhance the survival of animals. By analogy with acquired immunity, we term this system 'acquired resilience'. Evidence is reviewed that acquired resilience, like acquired immunity, fades with age. This fading is, we suggest, a major component of ageing. Understanding of acquired resilience may, we argue, open pathways for the maintenance of good health in the later decades of human life.
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http://dx.doi.org/10.1177/1559325818803428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6311597PMC
December 2018

Topical Treatment with Cord Blood Serum in Glaucoma Patients: A Preliminary Report.

Case Rep Ophthalmol Med 2018 25;2018:2381296. Epub 2018 Jul 25.

Emilia Romagna Cord Blood Bank-Transfusion Service, S.Orsola-Malpighi Teaching Hospital, Bologna, Italy.

Purpose: To report data which happened to be observed in two glaucoma patients treated with Cord Blood Serum (CBS) eye drops.

Design: A case report and retrospective data analysis.

Methods: CBS topical eye drops, characterized in advance for growth factors (GFs) content, were administered for two months with the aim to relieve their subjective symptoms, in two patients who had referred ocular surface discomfort, although in absence of any sign of keratopathy. As patients were also affected by advanced glaucoma at risk of vision loss and under treatment with hypotensive drugs, they had been also monitored over the same period with IOP controls and visual field tests in our unit.

Results: During subsequent visits, data from Mean Deviation and Pattern Standard Deviation in the visual fields were retrospectively collected and compared with before and after treatment with CBS, and an amelioration was observed.

Conclusions: CBS contains a combination of GFs, which potentially exert a neuroprotective action and elect CBS as an interesting natural source to be delivered in neurodegenerative ocular disorders. The incidentally observed amelioration in these two patients deserves further investigation in this respect.
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http://dx.doi.org/10.1155/2018/2381296DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6083596PMC
July 2018

A fully organic retinal prosthesis restores vision in a rat model of degenerative blindness.

Nat Mater 2017 06 6;16(6):681-689. Epub 2017 Mar 6.

Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy.

The degeneration of photoreceptors in the retina is one of the major causes of adult blindness in humans. Unfortunately, no effective clinical treatments exist for the majority of retinal degenerative disorders. Here we report on the fabrication and functional validation of a fully organic prosthesis for long-term in vivo subretinal implantation in the eye of Royal College of Surgeons rats, a widely recognized model of retinitis pigmentosa. Electrophysiological and behavioural analyses reveal a prosthesis-dependent recovery of light sensitivity and visual acuity that persists up to 6-10 months after surgery. The rescue of the visual function is accompanied by an increase in the basal metabolic activity of the primary visual cortex, as demonstrated by positron emission tomography imaging. Our results highlight the possibility of developing a new generation of fully organic, highly biocompatible and functionally autonomous photovoltaic prostheses for subretinal implants to treat degenerative blindness.
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http://dx.doi.org/10.1038/nmat4874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446789PMC
June 2017

Modulation of Type-1 and Type-2 Cannabinoid Receptors by Saffron in a Rat Model of Retinal Neurodegeneration.

PLoS One 2016 18;11(11):e0166827. Epub 2016 Nov 18.

Department of Medicine, Campus Bio-Medico University of Rome, Rome, Italy.

Experimental studies demonstrated that saffron (Crocus sativus) given as a dietary supplement counteracts the effects of bright continuous light (BCL) exposure in the albino rat retina, preserving both morphology and function and probably acting as a regulator of programmed cell death [1]. The purpose of this study was to ascertain whether the neuroprotective effect of saffron on rat retina exposed to BCL is associated with a modulation of the endocannabinoid system (ECS). To this aim, we used eight experimental groups of Sprague-Dawley rats, of which six were exposed to BCL for 24 hours. Following retinal function evaluation, retinas were quickly removed for biochemical and morphological analyses. Rats were either saffron-prefed or intravitreally injected with selective type-1 (CB1) or type-2 (CB2) cannabinoid receptor antagonists before BCL. Prefeeding and intravitreally injections were combined in two experimental groups before BCL. BCL exposure led to enhanced gene and protein expression of retinal CB1 and CB2 without affecting the other ECS elements. This effect of BCL on CB1 and CB2 was reversed by saffron treatment. Selective CB1 and CB2 antagonists reduced photoreceptor death, preserved morphology and visual function of retina, and mitigated the outer nuclear layer (ONL) damage due to BCL. Of interest, CB2-dependent neuroprotection was more pronounced than that conferred by CB1. These data suggest that BCL modulates only distinct ECS elements like CB1 and CB2, and that saffron and cannabinoid receptors could share the same mechanism in order to afford retinal protection.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166827PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5115823PMC
June 2017

Characterization of a Polymer-Based, Fully Organic Prosthesis for Implantation into the Subretinal Space of the Rat.

Adv Healthc Mater 2016 09 30;5(17):2271-82. Epub 2016 May 30.

Center for Synaptic Neuroscience and Technology, Fondazione Istituto Italiano di Tecnologia, Largo Giovanna Benzi 10, 16132, Genova, Italy.

Replacement strategies arise as promising approaches in case of inherited retinal dystrophies leading to blindness. A fully organic retinal prosthesis made of conjugated polymers layered onto a silk fibroin substrate is engineered. First, the biophysical and surface properties are characterized; then, the long-term biocompatibility is assessed after implantation of the organic device in the subretinal space of 3-months-old rats for a period of five months. The results indicate a good stability of the subretinal implants over time, with preservation of the physical properties of the polymeric layer and a tight contact with the outer retina. Immunoinflammatory markers detect only a modest tissue reaction to the surgical insult and the foreign body that peaks shortly after surgery and progressively decreases with time to normal levels at five months after implantation. Importantly, the integrity of the polymeric layer in direct contact with the retinal tissue is preserved after five months of implantation. The recovery of the foreign-body tissue reaction is also associated with a normal b-wave in the electroretinographic response. The results demonstrate that the device implanted in nondystrophic eyes is well tolerated, highly biocompatible, and suitable as retinal prosthesis in case of photoreceptor degeneration.
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http://dx.doi.org/10.1002/adhm.201600318DOI Listing
September 2016

Saffron reduces ATP-induced retinal cytotoxicity by targeting P2X7 receptors.

Purinergic Signal 2016 Mar 7;12(1):161-74. Epub 2016 Jan 7.

National Research Council, Institute of Biophysics, Via De Marini 6, 16149, Genoa, Italy.

P2X7-type purinergic receptors are distributed throughout the nervous system where they contribute to physiological and pathological functions. In the retina, this receptor is found in both inner and outer cells including microglia modulating signaling and health of retinal cells. It is involved in retinal neurodegenerative disorders such as retinitis pigmentosa and age-related macular degeneration (AMD). Experimental studies demonstrated that saffron protects photoreceptors from light-induced damage preserving both retinal morphology and visual function and improves retinal flicker sensitivity in AMD patients. To evaluate a possible interaction between saffron and P2X7 receptors (P2X7Rs), different cellular models and experimental approaches were used. We found that saffron positively influences the viability of mouse primary retinal cells and photoreceptor-derived 661W cells exposed to ATP, and reduced the ATP-induced intracellular calcium increase in 661W cells. Similar results were obtained on HEK cells transfected with recombinant rat P2X7R but not on cells transfected with rat P2X2R. Finally, patch-clamp experiments showed that saffron inhibited cationic currents in HEK-P2X7R cells. These results point out a novel mechanism through which saffron may exert its protective role in neurodegeneration and support the idea that P2X7-mediated calcium signaling may be a crucial therapeutic target in the treatment of neurodegenerative diseases.
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http://dx.doi.org/10.1007/s11302-015-9490-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749535PMC
March 2016

Cerium Oxide Nanoparticles Reduce Microglial Activation and Neurodegenerative Events in Light Damaged Retina.

PLoS One 2015 15;10(10):e0140387. Epub 2015 Oct 15.

Department of Applied Clinical Science and Biotechnology, University of L'Aquila, Via Vetoio, Coppito II, 67100 L'Aquila, Italy.

The first target of any therapy for retinal neurodegeneration is to slow down the progression of the disease and to maintain visual function. Cerium oxide or ceria nanoparticles reduce oxidative stress, which is known to play a pivotal role in neurodegeneration. Our aim was to investigate whether cerium oxide nanoparticles were able to mitigate neurodegeneration including microglial activation and related inflammatory processes induced by exposure to high intensity light. Cerium oxide nanoparticles were injected intravitreally or intraveinously in albino Sprague-Dawley rats three weeks before exposing them to light damage of 1000 lux for 24 h. Electroretinographic recordings were performed a week after light damage. The progression of retinal degeneration was evaluated by measuring outer nuclear layer thickness and TUNEL staining to quantify photoreceptors death. Immunohistochemical analysis was used to evaluate retinal stress, neuroinflammatory cytokines and microglial activation. Only intravitreally injected ceria nanoparticles were detected at the level of photoreceptor outer segments 3 weeks after the light damage and electoretinographic recordings showed that ceria nanoparticles maintained visual response. Moreover, this treatment reduced neuronal death and "hot spot" extension preserving the outer nuclear layer morphology. It is noteworthy that in this work we demonstrated, for the first time, the ability of ceria nanoparticles to reduce microglial activation and their migration toward outer nuclear layer. All these evidences support ceria nanoparticles as a powerful therapeutic agent in retinal neurodegenerative processes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0140387PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4607482PMC
June 2016

Slow-release drug delivery through Elvax 40W to the rat retina: implications for the treatment of chronic conditions.

J Vis Exp 2014 Sep 17(91):51563. Epub 2014 Sep 17.

ARC Centre of Excellence in Vision Science; John Curtin School of Medical Research, Australian National University; ANU Medical School, Australian National University;

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.
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http://dx.doi.org/10.3791/51563DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4828104PMC
September 2014

Combining neuroprotectants in a model of retinal degeneration: no additive benefit.

PLoS One 2014 23;9(6):e100389. Epub 2014 Jun 23.

Department of Biotechnology and Applied Clinical Science, University of L'Aquila, L'Aquila, Italy; ARC Centre of Excellence in Vision Science, The Australian National University, Canberra, Australia.

The central nervous system undergoing degeneration can be stabilized, and in some models can be restored to function, by neuroprotective treatments. Photobiomodulation (PBM) and dietary saffron are distinctive as neuroprotectants in that they upregulate protective mechanisms, without causing measurable tissue damage. This study reports a first attempt to combine the actions of PBM and saffron. Our working hypothesis was that the actions of PBM and saffron in protecting retinal photoreceptors, in a rat light damage model, would be additive. Results confirmed the neuroprotective potential of each used separately, but gave no evidence that their effects are additive. Detailed analysis suggests that there is actually a negative interaction between PBM and saffron when given simultaneously, with a consequent reduction of the neuroprotection. Specific testing will be required to understand the mechanisms involved and to establish whether there is clinical potential in combining neuroprotectants, to improve the quality of life of people affected by retinal pathology, such as age-related macular degeneration, the major cause of blindness and visual impairment in older adults.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100389PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4067315PMC
November 2015

Saffron and retina: neuroprotection and pharmacokinetics.

Vis Neurosci 2014 Sep 12;31(4-5):355-61. Epub 2014 May 12.

Dipartimento di Scienze Otorinolaringoiatriche e Oftalmologiche,University La Cattolica del Sacro Cuore,Roma,Italy.

Age-related macular degeneration (AMD) is a retinal neurodegenerative disease whose development and progression are the results of a complex interaction between genetic and environmental risk factors. Both oxidative stress and chronic inflammation play a significant role in the pathogenesis of AMD. Experimental studies in rats with light-induced photoreceptors degeneration demonstrated that saffron may protect photoreceptor from retinal stress, preserving both morphology and function and probably acting as a regulator of programmed cell death, in addition to its antioxidant and anti-inflammatory properties. Recently, a randomized clinical trial showed that in patients with early AMD, dietary supplementation with saffron was able to improve significantly the retinal flicker sensitivity suggesting neuroprotective effect of the compound. Here, we examine the progress of saffron dietary supplementation both in animal model and AMD patients, and discuss the potential and safety for using dietary saffron to treat retinal degeneration.
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http://dx.doi.org/10.1017/S0952523814000108DOI Listing
September 2014

The time course of action of two neuroprotectants, dietary saffron and photobiomodulation, assessed in the rat retina.

Am J Neurodegener Dis 2013 18;2(3):208-20. Epub 2013 Sep 18.

Department of Biotechnology and Applied Clinical Science, University of L'Aquila Italy.

Background: Dietary saffron and photobiomodulation (low-level infrared radiation, PBM) are emerging as therapeutically promising protectants for neurodegenerative conditions, such as the retinal dystrophies. In animal models, saffron and PBM, given in limited daily doses, protect retina and brain from toxin- or light-induced stress. This study addresses the rate at which saffron and PBM, given in daily doses, induce neuroprotection, using a light damage model of photoreceptor degeneration in Sprague Dawley (SD) rats.

Results: Rats were raised in dim cyclic (12 h 5 lux, 12 h dark) illumination, treated with saffron or PBM for 2-10 d, and then exposed to bright damaging light (1,000 lux for 24 h). After 1 week survival, the retina was assessed for photoreceptor death (using the TUNEL reaction), for surviving photoreceptor damage (thickness of the outer nuclear layer) and for the expression of a stress-related protein GFAP, using immunohistochemistry. Preconditioning the retina with saffron or PBM reduced photoreceptor death, preserved the population of surviving photoreceptors and reduced the upregulation of GFAP in Müller cells. At the daily dose of saffron used (1 mg/kg), protection was detectable at 2 d, increasing to 10 d. At the daily dose of PBM used (5 J/cm(2) at 670 nm) protection was detectable at 5 d, increasing to 7-10 d.

Conclusions: The results provide time parameters for exploration of the mechanisms and durability of the protection provided by saffron and PBM.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783833PMC
October 2013

Functional effect of Saffron supplementation and risk genotypes in early age-related macular degeneration: a preliminary report.

J Transl Med 2013 Sep 25;11:228. Epub 2013 Sep 25.

Dipartimento di Scienze Otorinolaringoiatriche e Oftalmologiche, Universita' Cattolica del Sacro Cuore, Lgo F, Vito 1, 00168 Roma, Italy.

Background: To determine whether the functional effects of oral supplementation with Saffron, a natural compound that proved to be neuroprotective in early age-related macular degeneration, are influenced by complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) risk genotypes.

Methods: Thirty-three early AMD patients, screened for CFH (rs1061170) and ARMS2 (rs10490924) polymorphisms and receiving Saffron oral supplementation (20 mg/day) over an average period of treatment of 11 months (range, 6-12), were longitudinally evaluated by clinical examination and focal electroretinogram (fERG)-derived macular (18°) flicker sensitivity estimate. fERG amplitude and macular sensitivity, the reciprocal value of the estimated fERG amplitude threshold, were the main outcome measures.

Results: After three months of supplementation, mean fERG amplitude and fERG sensitivity improved significantly when compared to baseline values (p < 0.01). These changes were stable throughout the follow-up period. No significant differences in clinical and fERG improvements were observed across different CFH or ARMS2 genotypes.

Conclusions: The present results indicate that the functional effect of Saffron supplementation in individual AMD patients is not related to the major risk genotypes of disease.
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http://dx.doi.org/10.1186/1479-5876-11-228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3850693PMC
September 2013

A polymer optoelectronic interface restores light sensitivity in blind rat retinas.

Nat Photonics 2013 May;7(5):400-406

Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy ; Department of Experimental Medicine, University of Genova, Genova, Italy.

Interfacing organic electronics with biological substrates offers new possibilities for biotechnology due to the beneficial properties exhibited by organic conducting polymers. These polymers have been used for cellular interfaces in several fashions, including cellular scaffolds, neural probes, biosensors and actuators for drug release. Recently, an organic photovoltaic blend has been exploited for neuronal stimulation via a photo-excitation process. Here, we document the use of a single-component organic film of poly(3-hexylthiophene) (P3HT) to trigger neuronal firing upon illumination. Moreover, we demonstrate that this bio-organic interface restored light sensitivity in explants of rat retinas with light-induced photoreceptor degeneration. These findings suggest that all-organic devices may play an important future role in sub-retinal prosthetic implants.
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http://dx.doi.org/10.1038/nphoton.2013.34DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4855023PMC
May 2013

Retinal function and CFH-ARMS2 polymorphisms analysis: a pilot study in Italian AMD patients.

Neurobiol Aging 2012 Aug 1;33(8):1852.e5-12. Epub 2012 May 1.

Istituto di Biochimica Clinica, Università Cattolica del S Cuore, Rome, Italy.

Two major susceptibility genes, complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2), have been implicated in age-related macular degeneration (AMD) pathogenesis. We analyzed the association between CFH rs1061170 and/or ARMS2 rs10490924 polymorphisms with central retinal function properties, as evaluated by focal electroretinogram (fERG). Forty early AMD patients, with preserved visual acuity and typical macular lesions, underwent fERG recording (in response to 41 Hz flicker stimuli presented to the central 18 degrees) and CFH/ARMS2 genotyping. Mean fERG amplitude and sensitivity decreased in patients carrying CFH rs1061170 polymorphism (p < 0.01), compared with wild type ones, although visual acuity and funduscopic features were similar across the 2 groups. No significant fERG phase changes were observed. No association was detected between ARMS2 (rs10490924) polymorphism and fERG parameters. Our findings indicate that CFH (rs1061170) polymorphism impacts significantly on retinal function in early AMD patients, and support the hypothesis that dysfunctional CFH might result in early retinal function loss due to a reduction in the immune antioxidant defense mechanism.
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http://dx.doi.org/10.1016/j.neurobiolaging.2012.03.008DOI Listing
August 2012

Gene and noncoding RNA regulation underlying photoreceptor protection: microarray study of dietary antioxidant saffron and photobiomodulation in rat retina.

Mol Vis 2010 Sep 3;16:1801-22. Epub 2010 Sep 3.

Division of Biomedical Sciences & Biochemistry, Research School of Biology, Australian National University, Sydney, Australia.

Purpose: To identify the genes and noncoding RNAs (ncRNAs) involved in the neuroprotective actions of a dietary antioxidant (saffron) and of photobiomodulation (PBM).

Methods: We used a previously published assay of photoreceptor damage, in which albino Sprague Dawley rats raised in dim cyclic illumination (12 h 5 lux, 12 h darkness) were challenged by 24 h exposure to bright (1,000 lux) light. Experimental groups were protected against light damage by pretreatment with dietary saffron (1 mg/kg/day for 21 days) or PBM (9 J/cm(2) at the eye, daily for 5 days). RNA from one eye of four animals in each of the six experimental groups (control, light damage [LD], saffron, PBM, saffronLD, and PBMLD) was hybridized to Affymetrix rat genome ST arrays. Quantitative real-time PCR analysis of 14 selected genes was used to validate the microarray results.

Results: LD caused the regulation of 175 entities (genes and ncRNAs) beyond criterion levels (p<0.05 in comparison with controls, fold-change >2). PBM pretreatment reduced the expression of 126 of these 175 LD-regulated entities below criterion; saffron pretreatment reduced the expression of 53 entities (50 in common with PBM). In addition, PBM pretreatment regulated the expression of 67 entities not regulated by LD, while saffron pretreatment regulated 122 entities not regulated by LD (48 in common with PBM). PBM and saffron, given without LD, regulated genes and ncRNAs beyond criterion levels, but in lesser numbers than during their protective action. A high proportion of the entities regulated by LD (>90%) were known genes. By contrast, ncRNAs were prominent among the entities regulated by PBM and saffron in their neuroprotective roles (73% and 62%, respectively).

Conclusions: Given alone, saffron and (more prominently) PBM both regulated significant numbers of genes and ncRNAs. Given before retinal exposure to damaging light, thus while exerting their neuroprotective action, they regulated much larger numbers of entities, among which ncRNAs were prominent. Further, the downregulation of known genes and of ncRNAs was prominent in the protective actions of both neuroprotectants. These comparisons provide an overview of gene expression induced by two neuroprotectants and provide a basis for the more focused study of their mechanisms.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2932490PMC
September 2010

Influence of saffron supplementation on retinal flicker sensitivity in early age-related macular degeneration.

Invest Ophthalmol Vis Sci 2010 Dec 4;51(12):6118-24. Epub 2010 Aug 4.

Dipartimento di Scienze Oftalmologiche e Otorinolaringologiche, Università Cattolica del S. Cuore, Rome, Italy.

Purpose: To evaluate the functional effect of short-term supplementation of saffron, a spice containing the antioxidant carotenoids crocin and crocetin, in early age-related macular degeneration (AMD).

Methods: Twenty-five patients with AMD were randomly assigned to oral saffron 20 mg/d or placebo supplementation over a 3-month period and then reverted to placebo or saffron for a further 3 months. Focal electroretinograms (fERGs) and clinical findings were recorded at baseline and after 3 months of saffron or placebo supplementation. fERGs were recorded in response to a sinusoidally modulated (41 Hz), uniform field presented to the macular region (18°) at different modulations between 16.5% and 93.5%. Main outcome measures were fERG amplitude (in microvolts), phase (in degrees), and modulation thresholds.

Results: After saffron, patients' fERGs were increased in amplitude, compared with either baseline or values found after placebo supplementation (mean change after saffron, 0.25 log μV; mean change after placebo, -0.003 log μV; P < 0.01). fERG thresholds were decreased after saffron supplementation but not placebo, compared with baseline (mean change after saffron, -0.26 log units; mean change after placebo, 0.0003 log units).

Conclusions: The results indicate that short-term saffron supplementation improves retinal flicker sensitivity in early AMD. Although the results must be further replicated and the clinical significance is yet to be evaluated, they provide important clues that nutritional carotenoids may affect AMD in novel and unexpected ways, possibly beyond their antioxidant properties. (ClinicalTrials.gov number, NCT00951288.).
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http://dx.doi.org/10.1167/iovs.09-4995DOI Listing
December 2010

Degeneration/re-organization coupling in retinitis pigmentosa.

Authors:
Silvia Bisti

Clin Neurophysiol 2010 Mar 11;121(3):270-1. Epub 2009 Dec 11.

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http://dx.doi.org/10.1016/j.clinph.2009.10.034DOI Listing
March 2010

Permanent functional reorganization of retinal circuits induced by early long-term visual deprivation.

J Neurosci 2009 Oct;29(43):13691-701

Department of Science and Biomedical Technology, University of L'Aquila, L'Aquila, Italy.

Early sensory experience shapes the functional and anatomical connectivity of neuronal networks. Light deprivation alters synaptic transmission and modifies light response properties in the visual system, from retinal circuits to higher visual centers. These effects are more pronounced during a critical period in juvenile life and are mostly reversed by restoring normal light conditions. Here we show that complete light deprivation, from birth to periods beyond the critical period, permanently modifies the receptive field properties of retinal ganglion cells. Visual deprivation reduced both the strength of light responses in ganglion cells and their receptive field size. Light deprivation produced an imbalance in the ratio of inhibitory to excitatory inputs, with a shift toward larger inhibitory conductances. Ganglion cell receptive fields in visually deprived animals showed a spatial mismatch of inhibitory and excitatory inputs and inhibitory inputs were highly scattered over the receptive field. These results indicate that visual experience early in life is critical for the refinement of retinal circuits and for appropriate signaling of the spatiotemporal properties of visual stimuli, thus influencing the response properties of neurons in higher visual centers and their processing of visual information.
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http://dx.doi.org/10.1523/JNEUROSCI.3854-09.2009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6665001PMC
October 2009

Saffron supplement maintains morphology and function after exposure to damaging light in mammalian retina.

Invest Ophthalmol Vis Sci 2008 Mar;49(3):1254-61

Department of Science and Biomedical Technology, University of L'Aquila, L'Aquila, Italy.

Purpose: To test whether the saffron extract (Crocus sativus L.) given as a dietary supplement counteracts the effects of continuous light exposure in the albino rat retina.

Methods: Three experimental groups of Sprague-Dawley rats were used. Experimental animals were prefed either saffron or beta-carotene (1 mg extract/kg/d) before they were exposed to bright continuous light (BCL) for 24 hours. Flash electroretinograms (fERGs) were recorded in control and treated rats the day before and 1 week after light exposure. At the end of the second recording session, the animals were killed and the retinas were quickly removed, fixed, cryosectioned, and labeled so that the thickness of the outer nuclear layer (ONL) could be analyzed. Changes in protein level and cellular localization of fibroblast growth factor (FGF)2 were determined by Western blot analysis and retinal immunohistochemistry, respectively. In a second series of experiments, rats were killed at the end of light exposure, and the amount of apoptotic figures in the ONL was assessed by terminal transferase-mediated deoxyuridine triphosphate (d-UTP)-biotin nick-end labeling (TUNEL). BCL induced DNA fragmentation, characteristic of dying cells, almost exclusively in the photoreceptor layer. The rate of photoreceptor death induced by BCL is expressed as the frequency of TUNEL-positive profiles per millimeter.

Results: The photoreceptor layer was largely preserved in saffron-treated animals because it was the fERG response. In addition, the rate of photoreceptor death induced by BCL appeared drastically reduced in treated animals. In beta-carotene prefeeding experiments, morphologic analysis showed preservation of the ONL similar to that obtained with saffron prefeeding, whereas the fERG response was unrecordable. Western blot analysis showed that exposure to light induced a strong upregulation of FGF2 in control and beta-carotene-treated rats, but s no change was noted in saffron-treated rats.

Conclusions: These results show that saffron may protect photoreceptors from retinal stress, maintaining both morphology and function and probably acting as a regulator of programmed cell death.
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http://dx.doi.org/10.1167/iovs.07-0438DOI Listing
March 2008

Gene expression and protein localization of calmodulin-dependent phosphodiesterase during ontogenesis of chick retina.

J Neurosci Res 2008 Apr;86(5):1017-23

Dipartimento di Biologia, Università di Genova, Genova, Italy.

Calmodulin-dependent phosphodiesterase (PDE1) is a key enzyme in cyclic nucleotides metabolism. We studied its gene expression and protein localization during retinal development in chick embryos. Western blot and densitometric analysis demonstrated that the expression of the three isoforms changed during development. PDE1A was highly expressed at the early stages and decreased as development proceeded. PDE1B expression remained relatively low and constant over time. PDE1C showed a prominent increase (13-fold) between embryonic day (E) 7 and E13, followed by a moderate increase between E13 and postnatal day (P) 1. The presence of the enzyme in the different retinal locations was strongly modulated by development. PDE1A immunostaining was first detected at the ganglion cell level (E7), then in the outer retina (E15-E21). At P5, the immunostaining was confined in the optic fiber layer. Isoform C immunolocalization followed the same inner-outer pattern as isoform A. At 5 days posthatching (P5), the immunoreactivity was restricted, as well as for the isoform A, in the optic fiber layer. The isoform B immunolabelling was low and evenly distributed across the retina at all stages. The different developmental profiles of PDE1A, PDE1B, and PDE1C induced a temporal modulation in cyclic nucleotides concentration, suggesting specific roles of this enzyme in the morphofunctional development of retinal circuitry.
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http://dx.doi.org/10.1002/jnr.21570DOI Listing
April 2008

Long-term dark rearing induces permanent reorganization in retinal circuitry.

Biochem Biophys Res Commun 2008 Jan 20;365(2):349-54. Epub 2007 Nov 20.

Dipartimento di Medicina Sperimentale, Università di L'Aquila, via Vetoio, Coppito 2, L'Aquila 67100, Italy.

Recent data challenged the assumption that light has little effect on retina development. Here, we report evidence that dark rearing permanently changes the synaptic input to GCs. A reduced spontaneous postsynaptic currents (SPSCs) frequency was found in retinal GCs from rats born and raised in the dark for three months. Glutamate antagonists (CNQX and AP-5) reversibly reduced SPSCs frequency in control and dark-reared (DR) retinae. The GABA antagonist picrotoxin (PTX) reduced SPSCs frequency in control retinas, but increased SPSCs frequency in DR, mainly by presynaptic action on excitatory currents. In DR animals exposed to normal cyclic light for 3 months, SPSCs frequency remained lower then in control rats and increased following PTX, suggesting that long-term dark rearing induces permanent modifications of the retinal circuitry. Our results strongly support the idea that light stimulation plays a role in establishing normal synaptic input to GCs.
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http://dx.doi.org/10.1016/j.bbrc.2007.10.204DOI Listing
January 2008